Remove std.algorithm.completeSort.

[Bernard Helyer]

Because it's apparent to me it's not going to be fixed. 
Furthermore, what does it gain you over sort(chain(a, b))? This 
is the first time in the 2 years it's been broken (and apparently 
Jesse is the only one that knew this! :D) someone has come to IRC 
with a problem regarding it. From that highly biased sample, I 
conclude it's not getting used. Anywhere. Or that bug would have 
more noise (it's the only result for 'completeSort' on bugzilla).

http://d.puremagic.com/issues/show_bug.cgi?id=4936